The present invention is related to a radio transceiver and in particular to a transceiver which can be controlled via a computer keyboard.
The current state of technology for radio transceivers is illustrated in FIG. 1. A transceiver 5 can be controlled by a full function keyboard 1 only when it is interfaced via an external computing device, such as an IBM PC/XT/AT microcomputer 2 which has a keyboard interface built into it. The microcomputer 2 has two serial RS-232C type output ports SO1 and SO2 which must be utilized in order to control the transceiver 5.
Control of the panel lights of the transceiver 5 and the sensing of the positions or states of switches thereon is handled by a microprocessor in the transceiver. In order to control the mode of the transceiver from the keyboard, the microcomputer must communicate with the microprocessor from serial port SO1 into serial port SI1 and to provide automatic code generation via the keyboard 1, the second serial port SO2 of the microcomputer 2 is utilized. However, a direct connection between the microcomputer and the transceiver is not possible and an additional interface must be added. This interface is known as a terminal unit 4 or a multimode data controller. The terminal unit 4 has a serial input SI2 connected to the serial output SO2 of the microcomputer and translates digital data from the microcomputer into an audio output at output AO which is connected into the microphone input MI of the transceiver 5. The terminal unit takes the digital input and by audio frequency shift keying (AFSK) it alternately applies one of two tones to the microphone input of the transceiver in response to the high and low state of the digital input signal. If it is desired to perform the same function when the transceiver receives data, then a similar terminal unit must be provided for decoding or demodulating the audio output signal from the transceiver and this data must be then fed into the microcomputer 2 so that it can be displayed on display 3.